Fuel cells which generate power through a chemical reaction between a fuel gas and an oxidizing gas are known. Among the fuel cells, a solid oxide fuel cell (SOFC) is a fuel cell which uses ceramics such as zirconia ceramics as an electrolyte and is operated using town gas, natural gas, petroleum, methanol, coal gasification gas, or the like as a fuel. Such an SOFC is known as a high-temperature fuel cell which has a high operating temperature of about 700° C. to 1000° C. in order to increase the ionic conductivity and has a high efficiency in wide applications (refer to Patent Documents 1 and 2). The SOFC is, for example, combined with an internal combustion engine such as a micro gas turbine (hereinafter, called an MGT) to form a combined power generation system, in which compressed air discharged from a compressor is supplied to an air electrode (cathode) of the SOFC, exhaust fuel gas of high temperature discharged from the SOFC is supplied to a combustor of the MGT via a blower to be combusted, and the turbine is rotated by combustion gas generated by the combustor, thereby achieving power generation with high power generation efficiency.